Method for purification of ortho-phenyl-phenol



Patented Dec. 8, 1931 Iran. STATES PATENT OFFICE EDGAR o. narrrolrpor, M D IIAND'QMIG IGAiv, .fis'sIsNoR TO THE pow CHE ICAL- COMPANY, on MIDLAND, MIGHIGAEA CORPORATION OF, MICHIGAN ivr'arrroij roa umm e QFIORTHO-PHENYL-IEHENQL' No Drawing.

The present invention concerns a method for the purification of orthophenylphenol.

As byproduct prepared; industrially from residual tar obtained inthe preparation of phenol by reacting ohlorobenzene with aqueous sodium hydroxide, orthophenylphenol usually has a decided color and odor and is contaminated with small amounts ofphenol andparaphenylphenol, together with alkaliinsoluble impurities, e. g. diphenyl oxide, diphenylene oxide, diphenyl, chlorodiphenyl, and the like. Separation of such impurities from the crude orthophenylphenol by fractional distillationnecessitates a lengthy procedure, and the final product still contains small amounts of impurities. Crystallization of said crude materialfrom organic solvents also requires a complicated procedure and entails solvent recovery. Consequently, such purification methods are unsatisfactory for industrial purposes wherea very pure product is desired. -I now have found that the crude o-rthophenylphenol maybe purified by treating the "same with aqueous caustic alkali, separating alkali-insoluble impurities from the liquor and'then crystallizing alkalimetal orthophenylphena'te from the alkaline solution, the alkali-metal-phenate and alkali metal paraphenylphenate remaining in solution. The crystalline salt may then :be separated fromthe residual liquor'and' converted into free orthophenylphenol in any suitable way, both the so-produoed salt and free ortho compound being substantially pure and. free from color-and odor.

- My invention, then, consists of the-method hereinafter fully described and particularly pointed out in theclaiins, the following description setting- :forth in detail several -modes of oarryingout my. invention, such disclosed modes lllustratlng, however, .but several of the various ways in. which the principle of my invention may be used. 1

In carrying out my invention, cru-deorthophenylpheno-l is dissolved in excess aqueous sodium hydroxide solution, as an example of a caustic alkali, tomake app-roximatelya 20,

.to 60 per cent solution containing excess base,

is then extracted with a solvent such I p as chlorobenzene, benzene, carbo'ntetraohlo 7 1 0 per cent of the water, and sodium ortho- Application" filed October 22,' 30- 's l i ride, ethylene dichloride, etc., to remove the above mentioned alkali-insoluble.impurities. The extracted solution may then beheated or otherwise treated to remove dissolved or residual traces of; solvent. therefrom, and evaporated or diluted until the concentration of the sodiumorthophenylphenate therein is such that the later may be crystallized there;

from by suit-able procedure, i. e., a concentrationof approximatelydO to per cent. T he solution may then becooled to a crystallizing temoerature for instance about 50 or lower depending on the strength of the sodium salt solution, and ,sodium orthophenylphenate crystallized therefrom in the form of crystals containing usually from threeto five molecules of water of crystallization, depending upon .the crystallization condition, which crystals may be separated from the mother liquor in any suitable way, such as by filtration orcentrifugation of the same, the so obtained crystals preferably being washed with an aqueous solution of the sodium, salt itself. If desired, the product may be recrystallized. The so obtained crystals may then be converted into free orthophenylphen'ol by dissolving the same in water, and acidifying the so obphenolrg The latterthen maybeseparated from the residual liquorand may or may'not be distilled, whereby pure orthophenylphenol is obtained in white form substantially free from impurity.

' The following. example represents'oneof the various ways'iof carrying out my; invention Eacample 1. 4l0O pounds of crude orthophenylphenol fractionated from phenol tar,

having a blue-color, a m. p. of about 52, and

containing about 5 per cent of impurities, was

dissolved in an aqueous solution of 104 pounds of sodium hydroxide in 597 pounds of water; by'warming. at about 60 C. The

so obtained solution was extracted three times with chlorobenzene, usingllO pounds of the latter for'each extraction, steam distilled to remove residualchlorobenzene and the recrystallization of the'salt gave on acidiphenylphenate crystallized therefrom at a temperature of from 17 down to 31 in amount equal to 389 pounds of the anhydrous salt, or an 86 per cent yield. The crystals were then dissolved in water, the so obtained solution acidified with hydrochloric acid, and the precipitated orthophenylphenol separated from the residual solution and dried, the final productfreezing at 56 to 57 C.

The residual mother liquorobtained from fication thereof a brownish material containing substantially all the alkali-soluble impurities including the smallamount of paraphenylphenol present in the original crude phenylphenol'. I

If the crude orthophenylphenol contains an appreciable amount of the corresponding para compound, say as much as 5-10 per cent of the latter, which has not previously been separated from the ortho compound by fractional distillation, such paraphenylphenol may be precipitated from the solution of alkali-metal salts previous to crystallization of the sodium orthophenylphenate, for instance as disclosed in my patent applications, Serial Nos. 411,7 60; 411,761; 411,762; filed December 5, 1929, by preferential hydrolysis, partial acidification, or by precipitation of a relatively insoluble-compound of the paraphenylphenol; Still another way of separating the paraand orthophenylphenols previous to crystallization of the sodium salt of the latter, is to treat the mixed free para and ortho compounds with alkali-metal base in amount sulficient'to dissolve substantially only the ortho and leave the para compound as a solid.

1 Briefly, my invention involves improvements in purifying orthophenylphenol, such improvementscomprising dissolving the same in aqueous alkali, removing alkali-insoluble impurities therefrom, crystallizing alkali-metal orthophenylphenate therefrom, and converting the latter into free orthophenylphenol, the resulting product being substantially white, free from undesirable odor, andpure. Furthermore, my invention, which has been described above as applying to the purification of orthophenylphenol obtained as a by-product fromthe hydrolysis of V benzene halides, may be utilized for the puribe employed. 1

fication of crude orthophenylphenol from other sources;

.my invention may be employed instead .of those explained, change'be'ing made as regards the improvements herein disclosed,

' Other modes of applying the principle of provided that the details stated by any of the following claims or the equivalent thereof I therefore particularly point out and distinctly. claim as my invention 1; The method of purifying orthophenylphenol which comprises reacting'ithe same with caustic alkali, crystallizing the so formed alkali-metal orthophenylphenate, and then converting the crystallized material into free orthophenylphenol.

2. The method of purifying orthophenylphenol which comprises reacting; the same with aqueous sodium hydroxide, crystallizing the thereby-formed sodium orthophenylphenate from the solution, and then convert.- ing the crystallized salt into free orthophenylphenol. i

8. The method of purifying orthophenylphenol which comprises dissolving the same in a slight excess of aqueous sodium hydroxide, crystallizing the thereby-formed sodium orthophenylphenate, separating crystals, and then acidifying the crystallized material in the presence of water to convert said salt into free orthophenylphenol.

4. The method of purifying orthophenylphenol which comprises dissolving the same in aqueous sodium hydroxide, separating alkali-insoluble material therefrom, ,crystallizing the thereby-formed sodium orthophenylphenate from the aqueous solution thereof, and converting saidsalt into free orthophenylphenol,

5. The method of purifying orthophenylphenol which comprises dissolving the same in aqueous sodium hydroxide, extracting the alkali-insoluble material with an organic solvent, crystallizing the thereby-formed so dium orthophenylphenate from the aqueous solution thereof, and converting said salt into free orthophenylphenol. I V

6. The method of purifying orthophenylphenol which, comprises dissolving the same in aqueous sodium hydroxide, extracting the alkali-insoluble material with an organic solvent, steam distilling the aqueous solution to remove residual organic solvent, crystalaqueous solution to approximately 40 to 60' per cent of sodium orthophenylphenate, crystallizing the latter, and converting-the crystallized material into free orthophenylphenol. t c

8. The method of purifying, orthophenylphenol which comprises dissolving the same in excess of aqueous sodium hydroxide to make approximately a 20 to 60 per cent solution, extracting the aqueous solution with a substantially water-insoluble organic solvent,

steam distilling residual organic solvent from the aqueous solution, adjusting the concentration of the solution to approximately 40 to 60 per cent of sodium orthophenylphenate,

crystallizing the latter, separating crystals,

and acidifying the crystallized material with mineral acid in the presence of water to form orthophenylphenol therefrom.

9. The method of purifying orthophenylphenol which comprises reacting the same with aqueous caustic alkali, separating paraphenylphenol therefrom, crystallizing alkalimetal orthophenylphenate from the residual 1 aqueous liquor, and then converting the crys tallized material phenol. V V V Signed by me this 18 day of October, 1930.

EDGAR C. BRITTON.

into free orthophenyl- 

